First Potential MFH - What Am I Missing??

[Eric Thomson]

Hello BP! I'm analyzing a deal that I hope will be my first MFH purchase. I need to know what other questions to ask and to figure out my max purchase price. Could use the help! I'm looking at 18 units (18 roofs) on 1 acre in a strong rental area (2 units are used as storage by seller, 1 unit unavailable due to fire damage). 100% of available units are occupied. All units are 2/1, 720sf. Tenants pay electric, owner pays water. 6 units are currently under Sec8. FMV is $675. None of seller's claims (below) have been verified yet. Here are my numbers:

Asking price: $575,000
Gross Income: $108,000/yr ($415-$900/mo, average $600/unit)
    *Will begin raising rents on day 1. Projected income: $194,000.
Owner Expenses: $53,000/yr
     $5,000/yr Taxes
    $5,500/yr Insurance
    $2,500/yr Electric
    $7,000/yr Water (adjusted for full 18 unit occupancy)
    $1,500/yr Gas
    $4,500/yr Dumpster/Landscaping
    $5,400/yr vacancy (5% - 100% occupancy of available units in strong rental area)
    $10,800/yr maintenance (10%)
Debt Service: ??? Have 20-25% for down payment. Seller offering owner financing. Also looking into other lenders. What interest rate should I expect?
Upfront Costs: $162,500
    20% down payment ($100,000 estimate)
    $20,000 to repair burn unit
    $5,000 rehab 2 storage units
    $2,500 x 13 units rehab
    $5,000 general common area rehab
Projected NOI: $151,800
Mgmt Fees: $10,800 (10% may be a little high)
Debt Service: $30,000 (estimated)
Cash Flow: $111,000/yr ($514/mo/roof)
Cash-on-Cash: 68%

So what expenses/numbers am I missing? Based on the numbers, what should my maximum asking price be? Where can I find a list of information I need to gather from seller for verification? And does anybody have a good property evaluation spreadsheet they are willing to share?

Thanks in advance for your help!